Performance Max Optimisation: 12 Fixes for Wasted Spend

Performance Max optimisation is the most common conversation we have with businesses who’ve handed Google the keys to their ad budget and are now watching the wheels spin without knowing why.

PMax is not a black box. It is a feedback loop. Feed it poor signals and it will optimise toward the wrong things. Feed it strong signals and it compounds into something genuinely powerful. Most accounts we audit are doing the former without realising it.

Here are 12 concrete PMax campaign tuning fixes — not theory, but specific things you can action this week.

The Core Problem with Most PMax Setups

Google’s PMax campaigns work by observing which users convert, then finding more users who look like them. This sounds simple, but it creates a critical problem: if your conversion tracking is weak, your audience signals are vague, or your asset groups are poorly themed, PMax will optimise toward signals that don’t actually represent your best customers.

The result is an account that spends money, generates some conversions, and looks healthy on the surface — while quietly wasting a significant share of budget on impressions and clicks that will never convert.

12 PMax Campaign Tuning Fixes

1. Separate your asset groups by product or service category

One asset group for everything is the most common mistake. PMax uses the assets in each group to determine relevance for different search queries. Mix unrelated products or services into the same group and Google cannot learn what “your customer” actually looks like.

2. Set audience signals — but don’t treat them as targeting

Audience signals tell Google where to start learning, not where to stay. Add your customer lists, high-intent custom intent segments (built around competitor URLs and relevant search terms), and any in-market audiences that match your buyers. Then let PMax expand from there.

3. Add brand exclusions as negative keywords at the account level

Without brand exclusions, PMax will spend on branded search terms that would have converted anyway. This inflates conversion numbers without adding incremental value. Set a negative keyword list that excludes your brand name and all variations.

4. Build negative keyword lists at the account level

PMax does not support traditional negative keywords at the campaign level in the same way as Search campaigns. But account-level negative keyword lists do apply. Audit your search terms reports, identify irrelevant or wasteful queries, and build a running exclusion list.

5. Turn off Final URL expansion if you don’t trust your site

When Final URL expansion is on, Google can send users to any page on your site it thinks is relevant, not just your landing page. This is powerful if your site is well-structured and conversion-optimised. It is dangerous if it is not. Audit where traffic is actually landing.

6. Use profit-based conversion values, not revenue

If you report revenue as your conversion value and you have varying margins across products or service tiers, PMax will optimise toward the highest revenue — not the highest profit. Configure conversion values to reflect the gross margin of each product or service where possible.

7. Upload high-quality creative across all formats

PMax will still run with two headlines and a logo if that’s all you give it — but performance will suffer. Provide the full range: multiple headlines, long headlines, descriptions, landscape images, square images, portrait images, and video if possible. Quality matters too. Generic stock images underperform brand-specific creative consistently.

8. Review asset performance ratings and cut D-rated assets

Inside your asset group details, each asset is rated: Best, Good, or Low. Assets rated Low are underperforming. Don’t leave them in the rotation — they drag down group-wide performance. Replace them with new variants and monitor.

9. Add Customer Match lists for retention targeting

Upload your existing customer email list as a Customer Match audience signal. This helps PMax distinguish between new customer acquisition and upsell/cross-sell signals, which is especially important if your lifetime value profile differs between new and returning customers.

10. Use Search Themes for first-party intent signals

Search Themes (a Google Ads asset at the asset group level) let you specify what searches you want a group to target. This gives Google direction without the rigidity of traditional keywords. Use them for high-value queries you want to be present for, especially in competitive categories where PMax might otherwise under-bid.

11. Check device performance splits in campaign segments

PMax aggregates performance across devices by default. Segment your data by device type. If mobile is consuming 60% of spend but generating 20% of conversions, something is wrong — either your mobile landing page experience, or PMax is simply finding lower-quality traffic on mobile for your category.

12. Run a cannibalism audit against your existing Search campaigns

PMax and Search campaigns can compete against each other in the same auction. Google’s own documentation states that Search campaigns take priority for exact match terms — but in practice, overlaps exist. Review which queries are converting in Search versus PMax and assess whether one campaign is cannibalising the other.

When None of This Moves the Needle

If you’ve worked through this list and performance is still flat, the issue is usually upstream of the campaign. Conversion tracking is broken or measuring the wrong event. The landing page is not converting. The product-market fit for what’s being advertised is not strong enough to support paid acquisition at current economics.

PMax is a signal amplifier. It cannot create demand that isn’t there — and no amount of PMax campaign tuning will rescue a fundamentally uneconomical offer.

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